Security is an important part of many computer networks. One aspect of network security is the ability to verify the identity of computers and/or their users. For example, in wireless networking, it is common for a client computer to be moved out of the operating range of one wireless base station and into the range of another wireless base station. When this occurs, it is often the case that the client computer receives a new network address from the new base station. To ensure that the client computer is still able to receive messages from other computers, the client computer informs a so-called “home agent” of its new address. A home agent is a computer (such as a server) that maintains a publicly known “home address” for the client computer and keeps track of the actual or “care-of” address of the client computer. When other computers wish to send messages to the client computer, they use the client computer's home address. The home agent then forwards the message to the client's “care-of” address. If a malicious entity such as a hacker wishes to intercept messages intended for the client computer, the malicious entity could simply pretend that it is the client computer and “inform” the home agent of its new care-of address. The home agent, if it was successfully tricked, would then forward the client computer's message to the malicious entity.
The above example illustrates the importance of being able to verify the identity of a computer in a wireless context. However, it is also important to be able to verify the identity of users and/or computers in wired scenarios as well.